A technique that uses an inkjet print head to preform printing is known for printing identification information such as characters, letters, marks or the like on a tablet. In a tablet printing apparatus using this technique, tablets are conveyed by a conveying device such as a conveyor. Ink (for example, edible ink) is ejected from a nozzle of the inkjet print head located above the conveying device toward each tablet passing under the print head to print identification information on the tablet.
Generally, when a tablet has not sufficiently dried and contains moisture, the frictional force is increased between the surface of the tablet and the conveying path. Accordingly, the tablet does not slide smoothly over the conveying path of the tablet printing apparatus, and may not flow along the conveying path. Particularly, in a supply device configured to feed a large number of tablets and including, for example, a hopper, a duct and a chute, in the case of feeding tablets from the duct to the chute having a narrow conveying path, if the tablets have not sufficiently dried and contain moisture, they do not slide smoothly and do not flow well, resulting in clogging of the tablets in the chute. This reduces the number of tablets to be conveyed, and thus the productivity decreases.
Besides, if the tablets have not sufficiently dried and contain moisture, when printing is performed on the tablets, the ink is less likely to permeate into the tablets. As a result, the ink on the tablets does not dry well, and the print is transferred to the tablets or the conveying path due to contact between the tablets, the tablets being conveyed upside down, or the like. This reduces the printing quality, and the apparatus is contaminated.